The present disclosure relates, in various embodiments, to an imaging member or apparatus and fuser components thereof. In particular, the present disclosure relates to a fuser member that includes an outer coating layer comprising a polydimethylsiloxane and a deflocculating agent. A fuser member in accordance with the present disclosure is suitable for use in electrostatographic and xerographic printing processes and is described with particular reference thereto.
In a typical electrostatographic reproducing apparatus, a light image of an original to be copied is recorded in the form of an electrostatic latent image upon a photosensitive member and the latent image is subsequently rendered visible by the application of electroscopic thermoplastic resin particles, which are commonly referred to as toner. The visible toner image is then in a loose powdered form and can be easily disturbed or destroyed. The toner image is usually fixed or fused upon a support, which may be the photosensitive member itself, or other support sheet such as plain paper.
The use of thermal energy for fixing toner images onto a support member is well known and methods include providing the application of heat and pressure substantially concurrently by various means such as, for example, a roll pair maintained in pressure contact, a belt member in pressure contact with a roll, a belt member in pressure contact with a heater, and the like. Heat may be applied by heating one or both of the rolls, plate members, or belt members. With a fixing apparatus using a thin film in pressure contact with a heater, the electric power consumption is small, and the warming-up period is significantly reduced or eliminated.
It is desired in the fusing process that minimal or no offset of the toner particles from the support to the fuser member take place during normal operations. Toner particles offset onto the fuser member may subsequently transfer to other parts of the machine or onto the support in subsequent copying cycles, thus increasing the background or interfering with the material being copied there. The referred to “hot offset” occurs when the temperature of the toner is increased to a point where the toner particles liquify and a splitting of the molten toner takes place during the fusing operation with a portion remaining on the fuser member. The hot offset temperature or degradation of the hot offset temperature is a measure of the release property of the fuser, and accordingly it is desired to provide a fusing surface, which has a low surface energy to provide the necessary release. To ensure and maintain good release properties of the fuser, it has become customary to apply release agents to the fuser member during the fusing operation. Typically, these materials are applied as thin films of, for example, silicone oils to prevent toner offset.
Another desired method for reducing offset is to impart antistatic and/or field assisted toner transfer properties to the fuser. To control the electrical conductivity of the release layer, however, the conformability and low surface energy properties of the release layer are often affected.
Known fuser coatings include high temperature polymers such as polytetrafluoroethylene, perfluoroalkoxy, fluorinated ethylene propylene, silicone rubber, fluorosilicone rubber, fluoroelastomers, and the like. These coatings have been found to have adequate release properties and control toner offset sufficiently. Problems, however, have resulted with known fuser member layers. For example, the fuser member may prematurely harden, which results in a life short fall. Some known fuser members have also been shown to exhibit a susceptibility to contamination, scratching and other damage. Further, silicone rubber layers tend to swell upon application of release agents. Moreover, fuser members have been shown to provide toner offset or inferior release capability, which allows for inappropriate copies and/or prints, and toner contamination to other parts of the machine.
U.S. Pat. No. 4,515,884 to Field et al. discloses a fuser member having a silicone elastomer-fusing surface, which is coated with a toner release agent, which includes an unblended polydimethyl siloxane.
U.S. Pat. No. 6,197,989 B1 to Furukawa et al. discloses a fluorine-containing organic silicone compound represented by a formula.
U.S. Pat. No. 5,736,250 teaches a crosslinked polysiloxane and fluoroelastomer layer.
U.S. Pat. No. 5,716,747 to Uneme et al. discloses a fluororesin coated fixing device with a coating of a fluorine containing silicone oil.
U.S. Pat. No. 5,698,320 to Ebisu et al. discloses a fixing device coated with a fluororesin, and having a fluorosilicone polymer release agent.
U.S. Pat. No. 5,641,603 to Yamazaki et al. discloses a fixing method using a silicone oil coated on the surface of a heat member.
U.S. Pat. No. 5,636,012 to Uneme et al. discloses a fixing device having a fluororesin layer surface, and using a fluorine-containing silicone oil as a repellant oil.
U.S. Pat. No. 5,627,000 to Yamazaki et al. discloses a fixing method having a silicone oil coated on the surface of the heat member, wherein the silicone oil is a fluorine-containing silicone oil and has a specific formula.
U.S. Pat. No. 5,624,780 to Nishimori et al. discloses a fixing member having a fluorine-containing silicone oil coated thereon, wherein the silicone oil has a specific formula.
U.S. Pat. No. 5,568,239 to Furukawa et al. discloses a stain proofing oil for heat fixing, wherein the fluorine-containing oil has a specific formula.
U.S. Pat. No. 5,463,009 to Okada et al. discloses a fluorine-modified silicone compound having a specific formula, wherein the compound can be used for oil-repellency in cosmetics.
U.S. Pat. No. 4,968,766 to Kendziorski discloses a fluorosilicone polymer for coating compositions for longer life.
One of the problems associated with fuser members coated with, for example, a fluoroelastomer, is that such coatings have a failure mode where the prints develop noticeable gloss variation as the coating wears. While even the worn areas of a fuser members often yield absolute gloss that is within the specification or tolerance limits of an imaging apparatus, a variation of as little as 2 gloss units is detectable by the human eye and may be deemed a failure or unacceptable result.
Another problem associated with fuser members coated with a fluoroelastomer is a defect known as barium sulfate defect. Barium sulfate is often added to and present on the surface of a fluoroelastomer polymer material to keep individual polymer pellets or particles from agglomerating. Barium sulfate, however, is otherwise not a necessary component to the functioning of the coating material. Barium sulfate defect results from agglomeration of insoluble barium sulfate present in the coating. Moreover, fuser member outer-layers produced by the flow coat process exhibit additional defects that occur particularly when the coatings are very thin, for example less than 50 micrometers in thickness. These defects include “snowflake agglomerates,” which are due to agglomeration of particles such as barium sulfate added to certain fluoroelastomers to prevent the fluoroelastomer pellets from sticking together, and “fisheyes,” which are typically 1 to 5 millimeter regions either devoid of a fluoroelastomer layer, or with a very thin fluoroelastomer layer. Such defects in the fuser member outer-layer can cause undesirable image defects on the printed copy, such as toner spots, toner picking (i.e., removal of toner leaving white spots), non-uniform gloss, hot offset, and poor image permanence. There exists a need for a flow coating solution that forms a fuser member outer-layer surface that is smooth and free of such defects.
Therefore, a need remains for fuser components for use in electrostatographic machines that have superior mechanical properties. Further, a need remains for fuser coatings having reduced susceptibility to contamination, scratching, and other damage. There is also a need for a coating layer that exhibits a relatively low roughness and is suitable for a fuser member. In addition, a need remains for a fuser component having a longer life. Even further, a need remains for a fuser component that maintains a high gloss.